/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */


int maxDepth(struct TreeNode* root){
    if(root == NULL) return 0;
    int l = (maxDepth(root->left)), r = (maxDepth(root->right));
    return (l > r ? l : r) + 1;
}
